Started out as some other type of rock, but have been substantially changed from their original igneous, sedimentary, or earlier metamorphic form. Metamorphic rocks form when rocks are subjected to high heat, high pressure, hot mineral-rich fluids or, more commonly, some combination of these factors.
Radioactive is the most penetrating nuclear radiation
Adding solvent or removing solute from a solution is called diluting. And a solution is said to be concentrated if it has more solute. The opposite of diluting is called concentrating. The measure of the amount of solute in a solution is expressed in concentration.
They are different by a phase shift of pi/2